Japanese utility Tokyo Gas has signed a long-term offtake agreement for a 49.7MW/202.1MWh battery energy storage system in Fukushima Prefecture, securing the full output of a project developed by Macquarie-owned Eku Energy that is now nearing commercial operation. The deal marks one of the first major utility-backed offtakes for a standalone merchant-scale battery in Japan, signaling that incumbent power companies are moving beyond pilot projects and into structured procurement of grid-scale storage as a core system asset.
The location carries symbolic weight. Fukushima, once synonymous with nuclear crisis, has become a focal point for Japan’s renewable energy rebuild, hosting large-scale solar and wind installations that increasingly require firming capacity. Tokyo Gas, a diversified energy player with deep roots in thermal generation and city gas supply, is positioning storage as a hedge against renewable intermittency and a tool for portfolio optimization in a market where capacity mechanisms are still evolving. The offtake structure provides Eku Energy with bankable revenue certainty, a critical enabler for financing merchant storage in a market that lacks a mature ancillary services framework.
Eku Energy, which acquired the project from a local developer and has advanced it through permitting and construction, represents a new class of independent storage platform entering Japan. Backed by Macquarie’s infrastructure capital, the company is pursuing a pipeline of projects across the country, betting that Japan’s power market reform — including the gradual introduction of capacity markets and wider balancing market participation — will create durable value for flexible assets. This first project serves as a proof point for that thesis, demonstrating that international storage specialists can navigate Japan’s regulatory, interconnection, and supply-chain complexities.
For the broader Japanese market, the agreement underscores a shifting dynamic: utilities are no longer waiting for policy mandates to adopt storage. Instead, they are proactively contracting capacity to manage balancing costs, defer grid upgrades, and capture arbitrage value as wholesale price volatility rises with higher renewable penetration. The Fukushima BESS, expected online imminently, will participate in both the capacity market and frequency regulation, offering a template for how hybrid revenue stacks can underwrite storage economics in Japan’s transitional market design.
Read the full report at Energy Storage News.